1. A preliminary study of this work has been published: Loh, T.-P.; Wei, L.-L. Tetrahedron Lett. 1998, 39, 323.
2. For comprehensive reviews: (a) Risch, N.; Arend, M.; Westermann, B. Angew. Chem., Int. Ed. Engl. 1998, 37, 1044 and references cited therein. (b) Tramontini, M.; Angiolini, L. Mannich-Bases, Chemistry and Uses; CRC: Boca Raton, FL, 1994 and reference cited therein. (c) Volkmann, R. A. In Comprehensive Organic Synthesis; Trost, B. M., Fleming, I., Eds.; Pergamon: Oxford, 1991; Vol. 1, p 355 and references cited therein.
3. (a) Danishefsky, S. J.; Chackalamannil, S.; Harrison, P.; Silvestri, M.; Cole, P. J. Am. Chem. Soc. 1985, 107, 2474.
4. (b) Morin, R. B. In Chemistry and Biology of β-Lactam Antibiotics; Gorman, M., Ed.; Academic Press: New York, 1982.
5. (a) Ojima, I.; Inaba, S.; Yoshida, K. Tetrahedron Lett. 1977, 18, 3643.